UBRARY  ^>fe. 

STATE  PLANT  BOARD 


^_^    u^-^^ 


Issued  March  7,  1911. 


U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ENTOMOLOGY— CIRCULAR  No.  134. 

L.  O.  HOWARD.  Entomologist  and  Chief  of  Bureau. 


DAMAGE   TO    TELEPHONE    AND   TELEGRAPH 
POLES  BY  WOOD-BORLNG  LNSECTS. 


T.  E.  SNYDER, 

Agent  and  Expert. 


r5;j8°— u 


WASHINGTON   :   GOVERNMENT   PRINTING  OFFICE  :   1911 


S5 


BVREA  r  OF  ENTOMOLOGY. 

L.  O.  HowAKD,  Entomologist  and  Chief  of  Bureau. 

C.  L.  Marlatt,  Entomologifit  and  Acting  Chief  in  Absence  of  Chief. 

R.  S.  Cliftox,  Executive  Assistant. 

W.  F.  Tastet,  Chief  Clerk. 

F.  H.  Chittenden,  in  charge  of  truck  crop  and  stored  product  insect  investigations. 

A.  D.  Hopkins,  in  charge  of  forest  insect  investigations. 

W.  D.  Hunter,  in  charge  of  southern  field  crop  insect  investigations. 

F.  M.  Webster,  in  charge  of  cereal  and  forage  insect  investigations. 

A.  L.  Quaintance,  in  charge  of  deciduous  fruit  insect  investigations. 

E.  F.  Phillips,  in  charge  of  bee  culture. 

D.  M.  Rogers,  in  charge  of  preventing  spread  of  moths,  feld  work. 

RoLLA  P.  Currie,  in  charge  of  editorial  irork. 

Mabel  Colcord,  librarian. 

Forest  Insect  Investigations. 

A.  D.  Hopkins,  in  charge. 

H.  E.  Burke,  J.  L.  Webb,  Josef  Brunner,  S.  A.  Rohwer,  T.  E.  Snyder.  \\'.  1). 

Edmonston,  W.  B.  Turner,  agents  and  experts. 
Mary  E.  Faunce,  preparator. 
William  Middleton,  Mary  C.  Johnson,  student  assistants. 


Circular  No.  134.  iss"t-.i  March  7.  rjii. 

United  States  Department  of  Agriculture, 

BUREAU  OF  ENTOMOLOGY. 
L.  O.  HOWARD,  Entomologist  and  Chief  of  Bureau. 


DAMAGE    TO   TELEPHONE   AND    TELEGRAPH    POLES  BY 
WOOD-BORING  INSECTS.^ 

By  T.  E.  Snyder, 
Agent  and  Expert. 

It  has  recently  been  determined  tlirougb  special  nivestigations  con- 
ducted by  the  Bureau  of  Entomology,  in  cooperation  with  telephone 
and  telegraph  companies,  that  serious  and  extensive  damage  is  being 
done  in  certain  localities  to  standing  poles  by  wood-boring  insects. 
The  object  of  this  circular  is  to  give  information  on  the  principal  as 
well  as  other  types  of  insect  injury  to  poles,  so  that  line  inspectors 
may  distinguish  the  various  types  and  determine  and  report  on  the 
character  and  extent  of  the  damage. 

CHARACTER    OF    THE    INJURY. 

The  principal  injury  to  the  poles  consists  in  large  mines  in  the  wood 
near  the  line  of  contact  with  the  ground,  necessitating  the  frequent 
resetting  or  even  the  replacement  of  the  damaged  poles.  These 
irregular  mines  (fig.  1)  run  both  transversely  and  longitudinally 
throughout  the  heartwood,  and  are  sometimes  7  inches  long,  but 
vary  in  length.  This  injury  is  usually  in  the  outer  layers  of  the 
wood  for  a  distance  of  from  2  to  3  feet  below  and  sometimes  from  1 
to  2  feet  above  the  line  of  contact  of  the  pole  with  the  surface  of  the 
ground.  The  greatest  damage  is  to  that  area  just  below  and  just 
above  the  surface  of  the  ground;  here  the  conditions  of  air  and 
moisture  are  most  favorable.  The  mines,  often  very  close  together, 
completely  honeycomb  the  wood  in  a  zone  from  3  to  4  inches  in  from 
the  exterior  of  the  poles  (fig.  3);  this  so  weakens  the  poles  that  they 
break  off  close  to  the  surface  of  the  ground.     The  basal  2  feet  is 

'  Revised  extracts  from  Bulletin  94,  Part  I,  Bureau  of  Entomology,  U.  S.  Department  of  Agriculture, 
1910. 

77538°— Cir.  134—11  1 


UBRARY 
OTATE  PLANT  BOARD, 


INSECT   DAMAGE    TO    TELEPHONE   AND    TELEGRAPH    POLES. 


^m' 


Fin.  1.— Work  of  the  pole  borer  (J'urandra  brunnia  Fab.)  in  in  untreated  eliestniit  pole:  a,  (lallery  of  the 
jMjle  borer,  showing;  jiiipal  chamber  witli  the  etitranee  phijjged  with  eNcclsior-like  \voo«l  fibers;  work  near 
\):\s(?  of  iK)le,  below  jjround.  b,  Mines  of  the  pole  borer  near  surface  of  ground.  Natural  size.  (Author's 
ilhistration.) 


INSECT    DAMAGE    TO    TELEPHOXE    AND    TELEGRAPH    POLES.  3 

usualh'  sound.  Even  if  the  damage  is  not  serious  enough  to  cause 
the  poles  to  break  off  under  strain,  they  are  hkely  to  go  down  during 
any  storm,  and  thus  put  the  wire  service  out  of  commission;  such 
damaged  poles  are  a  serious  menace  along  the  right  of  way  of  rail- 
roads. Poles  that  appear  sound  on  the  exterior  may  have  the 
entire  basal  interior  riddled,  and  the  damage  is  not  noticed  until  the 
poles  break  off.  If  merely  isolated  poles  are  injured  so  as  to  cause 
them  to  break  off,  they  simply  lean  over,  but  if  several  adjacent  poles 
are  affected,  especially  where  there  is  any  unusual  strain,  that  por- 
tion of  the  line  is  very  hkely  to  go  down. 

THE    PRIXCIPAL    INJURIOUS    SPECIES. 

The   principal   injurious   species   is    the    chestnut    telephone-pole 
borer,  or  pole  borer/  which  is  an  elongate,  creamy-white,  wrinkled, 


Fig.  2. — /,  Tho  pole  borer:  Male  and  female  beetles.    .\  The  pole  borer:  Young 
larva?.    /,  Slightly  enlarged;  ?,  twice  natural  size.    (Author's  illu.stration.) 

round-headed  grub  or  larva  (fig.  '2,2).  It  hatches  from  an  egg  depos- 
ited by  an  elongate,  mahogany -brown,  shiny,  flattened,  winged 
beetle,  from  two-flfths  to  four-flfths  of  an  inch  in  length  (fig.  2,  1). 
It  appears  tliat  the  eggs  are.  deposited  from  August  to  October  in 
the  outer  layers  of  tlie  wood  of  the  pole  near  the  surface  of  the 
ground.  The  young  borers,  upon  hatching,  excavate  shallow  gal- 
leries in  the  sapwood,  then  enter  the  heartwood,  tlie  mines  being 
gradually  enlarged  as  tliey  develop.  As  they  proceed  they  closely 
pack  tlie  fine  boring  dust  behind  them.  Tliis  peculiar  semidigested 
boring  dust,  which  is  characteristic  of  their  work,  is  reddish  to  dun- 

'  Parandra  hrunnca  Fab.  Since  the  publication  of  Bulletin  94,  Part  I,  of  this  Bureau,  this  borer,  first 
found  to  be  injurious  to  chestnut  telephone  poles,  has  been  found  injurious  to  arborvitae  poles,  and  as  it 
also  injures  telegraph  poles,  the  name  "pole  borer"  is  more  appropriate  and  comprehensive. 


4  IXSECT   DAMAGE    TO    TELEPHONE    AXD    TELEGRAPH    POLES. 

nisli  yellow  in  color  and  has  a  claylike  consistency.  The  burrows 
eventually  end  in  a  broad  chamber,  the  entrance  to  which  is  plugged 
\Wth  excelsiorlike  fibers  of  wood.  Here  is  formed  the  restino:  staoje, 
or  pupa,  which  transforms  to  the  adult  beetle.  Often  all  stages,  from 
very  young  grubs  only  about  one-fourth  inch  long  to  full-grown 
grubs  over  1  inch  long,  pup?e,  and  adults  in  all  stages  to  maturity 
are  present  in  the  same  pole.  Adidts  have  been  found  living  from 
July  to  September. 

The  insect  attacks  poles  that  are  perfectly  sound,  but  will  work 
where  the  wood  is  decayed;  it  will  not,  however,  work  in  wood  that 
is  ''sobby"  (wet  rot),  or  in  very  ''doty"  (punky)  wood.  It  has  not 
yet  been  determined  just  how  soon  the  borers  enter  the  poles  after 
they  have  been  set  in  tlie  groinid.     However,  p(  les  tliat  had  been 


Fin.  3.— Damage  to  an  untreated  chestnut  telegraph  pole  near  surfai-o  of  ground 
by  the  pole  borer.    (Author's  illustration.) 

stanchng  only  four  or  five  years  contained  larvte  and  aihilts  of  this 
borer  in  the  heartwood,  and  poles  that  liad  been  set  in  the  ground 
for  only  two  years  contained  young  larva^  in  the  outer  layer's  of  the 
wood. 

The  ])resence  of  the  borers  in  injurious  numlxM's  can  l)e  (h'ter- 
mined  only  by  removing  the  earth  from  about  the  base  of  the  i)ole; 
the  large  holes  iiuide  when  the  a(hdts  come  out  are  found  near  the 
hue  of  contact  with  the  soil.  Often  large,  coarse  borings  of  wood 
hber  project  from  these  exit  holes.  Sometinu^s  the  old  dead  parent 
a(hdts  are  found  on  the  extcM'ior  of  the  poh's  uiKhM-ground.  During 
August  the  young  achihs  iiiny  he  found  in  shallow  depressions  on  the 
exterior  of  j)ol('s  below  the  gi-onnd  surface. 


INSECT    DAMAGE    TO    TELEPHONE    AND    TELEGRAPH    POLES.  5 

INJURY    BY    OTHER    INSECTS. 

It  is  not  to  be  concluded  that  injury  by  the  pole  borer  is  the  only 
type  of  insect  damage  to  poles.  Indeed,  a  very  common  injury  is  by 
white  ants,  or  termites.  In  lines  from  10  to  12  years  old  serious 
damage  by  these  insects  occurred  in  as  high  as  15  per  cent  of  the 
poles,  and  their  work  is  often  present,  at  least  superficially,  in  as 
high  as  75  per  cent  of  the  poles  under  all  conditions  of  site.  The 
damage,  however,  is  usually  to  the  outer  layers  of  the  wood,  where  it 
is  moist  or  there  is  incipient  decay,  and  is  more  superficial  and  local- 
ized than  that  of  the  pole  borer.  Xevertheless,  the  sound  heartwood 
of  poles  is  often  completely  honeycombed,  especially  at  the  base.  The 
work  of  white  ants  is  found  both  in  sound  wood,  ''doty"  wood,  and 
''sobby  "  wood.  Sometimes  a  large  channel  runs  up  through  the  core 
of  the  heart  and  the  sides  are  plastered  with  clay,  forming  a  hollow 
tube  w4th  several  longitudinal  interior  galleries.  Their  work  often 
extends  from  2  to  4  feet  above  the  surface  of  the  ground.  They 
leave  the  outer  shell  of  the  wood  intact  and  work  up  through  the 
longitudinal  weathering  checks,  covering  the  exterior  of  the  pole  with 
earth  to  exclude  the  light.  AYliite  ants  will  damage  poles  that  have 
been  set  in  the  ground  only  two  years.  Evidently  they  enter  the 
pole  from  below  the  surface  of  the  ground. 

Injury  by  a  giant  round-headed  borer  is  sometimes  found  in  chest- 
nut poles.  The  large  mines  of  this  borer  are  found  in  the  sound 
and  decayed  wood  of  poles.  Often  where  there  is  rot  present  the 
heartwood  near  the  surface  of  the  ground  is  completely  honey- 
combed by  this  borer. 

Longitudinal  weathering  checks  in  chestnut  poles  are  often  widened, 
and  other  defects  enlarged  by  large,  black  carpenter  ants  and  other 
smaller  black  ants,  which  thus  hasten  decay. 

KNOWN  EXTENT  OF  THE  DAMAGE. 

The  pole  borer  has  seriously  damaged  as  high  as  10  to  15  per  cent 
of  the  chestnut  poles  which  have  been  set  in  the  ground  for  from  10 
to  12  years  in  lines  in  North  Carolina,  Virginia,  West  Virginia,  Mary- 
land, and  the  District  of  Columbia.  It  has  only  recently  been  deter- 
mined that  it  has  also  seriously  damaged  a  considerable  proportion 
of  the  arborvitse^  telephone  poles  in  part  of  a  line  in  Illinois.  It  is 
evident,  then,  that  this  insect  is  an  important  factor  in  decreasing  the 
normal  length  of  service  of  chestnut  and  arborvitae  poles. 

POSSIBILITIES    OF    PREVENTING    DAMAGE    TO    POLES. 

Methods  of  treating  poles  superficially  by  brushing  with  various 
preservatives  have  proved  to  be  temporarily  efficient  in  keeping 
out  wood-boring   insects,  if   the  work   is   thoroughly  done  and  not 

I  Thuja  occidentalis. 


6  INSECT    DAMAGE    TO    TELEPHONE    AND    TELEGRAPH    POLES. 

onlv  the  butt,  but  also  the  basal  area,  is  treated.  If  the  pole  is  not 
thoroucrhlv  brushed,  the  pole  borer  and  other  insects  enter  through  the 
untreated  or  imperfectly  treated  portions,  especially  through  weath- 
erino-  checks  and  knots.  Where  the  base  is  left  untreated,  insects, 
espedallv  white  ants  or  termites,  enter  the  pole  from  below  ground 
and  avoiding  the  treated  portions,  come  right  up  through  the  pole. 
Imprecrnating  the  poles  with  creosote  by  some  standard  process 
(either  bv  the  open-tank  or  bv  a  cyhnder-pressure  process)  will  keep 
out  wood-boring  insects.  In  the  open-tank  method  only  the  area  most 
subject  to  the  attacks  of  wood-boring  insects  (i.  e.,  the  basal  8  feet) 
is  treated,  while  by  the  cylinder-pressure  processes  the  entire  pole  is 

impregnated.  „ 

Therefore  to  efTectuallv  protect  poles  from  the  depredations  ot 
wood-borin-  insects  it  is  recommended  that  they  be  impregnated  with 
creosote  by  either  the  "open-tank"  process  or  by  a  cylinder-pressure 
process. 

\T^tArr^v<Hl  •  UNIVERSITY  OF  FLORIDA 

Appro\  (.  ti .  ..  . ,,, ,., ,,.,,  mil  III  III!  nil  III  mil  III  mil 

James  Wilson,        _  |||||||||||||||||||||iillll||||||||||li 

Secretary  of  Agriculture.  3  -|262  09228  2796 

Washington,  D.  C,  January  U,  i^^^- 

o 


